Semiconductor memory devices store data and/or program code in personal computer systems, embedded processor-based systems, video image processing circuits, communications devices, and the like. A ferroelectric memory device is one type of semiconductor memory device.
Ferroelectric memory devices provide non-volatile data storage by employing ferroelectric capacitors that are constructed using ferroelectric dielectric material that may be polarized in one direction or another in order to store a binary value. The ferroelectric effect allows for the retention of a stable polarization in the absence of an applied electric field due to the alignment of internal dipoles within perovskite crystals in the ferroelectric material. This alignment may be selectively achieved by application of an electric field in a first direction that exceeds a coercive field of the material. Conversely, reversal of the applied field reverses the internal dipoles, wherein the response of the polarization of a ferroelectric capacitor to the applied voltage may be plotted as a hysteresis curve.
Given the technological complexity of ferroelectric memory devices, these products require significant capital expenditures to be developed and successfully delivered to the marketplace. Thus, developers rely on strong intellectual property rights in this arena to allow them to rationalize and protect the huge capital expenses involved.